This invention relates to a composite structure adapted to provide thermal insulation for windows.
Window heat loss accounts for about 20-40% of building space heating costs. With continuing increases in fuel costs, existing structures require an inexpensive and practical means for converting single pane glass windows to thermal insulators. Presently employed means include double paned windows constructed to form a sealed air space between the panes. Alternatively, an equivalent second (storm) window is added to function in conjunction with the window to form an insulating air space. The present insulating means are undesirable since they are expensive to make and to install. Furthermore, even though these double pane arrangements reduce heat loss due to conduction through the outside glass pane, there is still substantial heat loss caused by convection of the air within the air space which promotes conduction heat loss through the outside pane.
It would be desirable to promote a means for thermally insulating glass windows with little or no structural modification. Furthermore, it would be desirable to provide a glass thermal insulation means which requires little or no labor costs and which can be produced without the need for special installation tools. In addition, it would be desirable to provide a thermal insulation means for glass windows which can be modified easily to change its light transmission or reflectance characteristics thereby to permit its preferential use at different exposures of a building. Furthermore, it would be desirable to provide such a thermal insulation means which minimizes convection heat loss.